A switching element made up of a field effect transistor (FET) with high operating voltage and being able to pass a large current, that is, a so-called power transistor has been widely used in, for example, power sources of an information device, home electronics and an in-vehicle device and a motor-drive device.
A switching element using a cascode connection has been known as the switching element mentioned above. The switching element using a cascode connection includes, for example, a normally-on junction field effect transistor (JFET) and a normally-off metal oxide semiconductor field effect transistor (MOSFET), and the normally-on junction FET and the normally-off MOSFET are connected in series.
In the technique disclosed in Japanese Patent Application Laid-Open Publication No. 2014-512765 (Patent Document 1), a switch has a first normally-on semiconductor device and a first normally-off semiconductor device, and a source of the first normally-on semiconductor device is connected to a drain of the first normally-off semiconductor device.
In the technique disclosed in Japanese Patent No. 5012930 (Patent Document 2), a hybrid power device has a normally-on SiC-JFET and a normally-off Si-MOSFET, and a source of the SiC-JFET and a drain of the Si-MOSFET are connected, so that the SiC-JFET and the Si-MOSFET are cascode-connected.
In the technique disclosed in Japanese Patent Application Laid-Open Publication No. 2014-3110 (Patent Document 3), a semiconductor device has a normally-off silicon transistor and a normally-on compound transistor whose source-drain path is coupled between a pair of terminals through a source-drain path of the silicon transistor.